甲醛后肢致炎大鼠中脑导水管周围灰质内勿动蛋白-A和降钙素基因相关肽mRNA表达的变化

目的 观察甲醛后肢致炎大鼠中脑导水管周围灰质(PAG)内勿动蛋白-A(Nogo-A)和降钙素基因相关肽(CGRP)及其受体mRNA表达的变化。方法 大鼠单侧后肢sc给予2%甲醛0.1ml引起炎症反应,第3天用热和压力刺激方法,检测大鼠后爪缩爪潜伏期变化,确定甲醛致炎痛敏模型成功。分别在致炎后第3天和第7天取出大鼠PAG,采用实时定量PCR检测PAG内Nogo-A、CGRP、降钙素受体样受体(CLR)和受体调节蛋白1(RAMP1)mRNA的表达。结果 正常大鼠PAG内Nogo-A,CGRP,CLR和RAMP1mRNA均有不同程度的表达。甲醛致炎第3天,与正常大鼠比较,压力和热刺激方法测定大鼠缩爪潜伏期均显着缩短(P<0.01),并且致炎痛敏大鼠PAG内Nogo-AmRNA表达显着降低(P<0.01),CGRP,CLR和RAMP1mRNA表达显着增加(P<0.01).甲醛致炎第7天,CGRPmRNA表达恢复到正常水平,但Nogo-AmRNA表达仍低于正常水平(P<0.01),CLR和RAMP1mRNA表达仍高于正常水平(P<0.01)。结论 甲醛致后肢炎性痛敏大鼠PAG内Nogo-A表达显着下降,CGRP,CLR 和RAMP1mRNA表达升高;并且随炎症的减轻,CGRPmRNA表达逐渐恢复正常。这些变化可能与大鼠PAG涉及炎症反应或痛觉调制过程有关。

Changes of neurite outgrowth inhibitor-A and calcitonin gene-related peptide mRNA expression in periaqueductal gray of hindpaw inflammatory rats induced by formaldehyde

OBJECTIVE To investigate the mRNA expression changes of neurite outgrowth inhibitor-A(Nogo-A), calcitonin gene-related peptide(CGRP) and CGRP receptor in the periaqueductal gray of formaldehyde-induced inflammatory rats. METHODS The hyperalgesia of inflammation was induced in rats by receiving 2% formaldehyde (sc 0.1 ml) in the unilateral hindpaw hypodermically. On the 3rd day, hindpaw withdrawal latencies in response to both the thermal and mechanical stimulation were measured, and on the 3rd and 7th days respectively after inflammation the periaqueductal gray of rats was separated. The real-time quantitative PCR was used to detect mRNA expression of Nogo-A, CGRP, calcitonin receptor-like receptor (CLR), and receptor activity-modifying proteins 1 (RAMP1) in the periaqueductal gray of rats. RESULTS There was gene expression of Nogo-A, CGRP, CLR and RAMP1 in the periaqueductal gray of normal rats. On the 3rd day after inflammation, compared with the control group, the hindpaw withdrawal latencies in response to both thermal and mechanical stimulation significantly decreased (P<0.01), the mRNA expression of Nogo-A significantly decreased (P<0.01), and the expression of CGRP, CLR and RAMP1 was significantly increased (P<0.01) in the periaqueductal gray of inflammatory rats. On the 7th day after inflammation, the CGRP mRNA expression returned to the level of normal rats, but the mRNA expression level of Nogo-A, CLR and RAMP1 didn't. The level of Nogo-A was lower (P<0.01), but that of CLR and RAMP1 was still higher (P<0.01) than normal levels. CONCLUSION The mRNA expression of Nogo-A significantly decreases, but the expression of CGRP, CLR and RAMP1 significantly increases in the periaqueductal gray of formaldehyde-induced inflammatory hyperalgesia rats. Along with the relief of inflammation, the mRNA expression of CGRP gradually returns to normal. These changes may be related to the process of inflammation or pain modulation in rat periaqueductal gray.